Melting Himalayan glaciers contaminated by legacy atmospheric depositions are important sources of PCBs and high-molecular-weight PAHs for the Ganges floodplain during dry periods

Melting glaciers are natural redistributors of legacy airborne pollutants, affecting exposure of pristine proglacial environments. The data from this study shows that melting Himalayan glaciers can be major contributors of polychlorinated biphenyls (PCBs) and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) for surface water in the Gangetic Plain during the dry season. Glacial emissions can exceed in some cases inputs from diffuse sources within the catchment. The authors analysed air, deposition and river water in several sections along the Ganges River and its major headwaters. The predominant glacial origin of these contaminants in the Himalayan reach was demonstrated using air-water fugacity ratios and mass balance analysis. The proportion of meltwater emissions compared to pollutant discharge at downstream sections in the central part of the Gangetic Plain was between 2 and 200%. The authors concluded that by remobilising legacy pollutants from melting glaciers, climate change can enhance exposure levels over large and already heavily impacted regions of Northern India.

Authors: Sharma BM, Nizzetto L, Bharat GK, Tayal S, Melymuk L, Sá?ka O, P?ibylová P, Audy O, Larssen T. ;Full Source: Environmental Pollution. 2015 Aug 24;206:588-596. doi: 10.1016/j.envpol.2015.08.012. [Epub ahead of print] ;